Not applicable.
This invention relates generally to the pneumatic conveying of flexible fabrics such as uniforms, table linens and other articles handled by commercial laundries and industrial uniform processing plants, as well as other fabric items that are conveyed between different locations in other types of applications. More particularly, the invention is directed to a method and apparatus that makes use of a venturi to provide a suction force for pulling fabrics through conveyor tubes and a closed loop return conduit providing an air return path from a vent to the suction side of a blower that feeds air to the venturi.
Commercial laundries handle large volumes of a variety of materials, including table cloths, napkins and other table linens used in restaurants and other food service operations. Uniforms worn by manufacturing and service personnel and others are examples of other types of articles that are typically laundered by commercial laundries. A significant part of the operation of commercial laundries involves sorting the different types of articles while keeping track of where they came from and the number and types of articles that are to be laundered.
Typically, the items are sorted at a sorting table or other sorting station. Like articles are then conveyed pneumatically to another location where they are further handled. Because flexible fabrics tend to ball up when pushed through pneumatic conveyor tubes, they are usually pulled through the tubing system by suction. The type of system that is most prevalent in commercial laundries makes use of vacuum bins that are each provided with a large vacuum motor. The vacuum that is applied to the vacuum bins pulls the laundry items through the conveyor tubes and into the bins.
Although vacuum bins of this type have achieved considerable popularity, they have not been satisfactory in all respects. Their relatively high cost adds appreciably to the capital costs of the laundry equipment. Furthermore, it is necessary for the items in the vacuum bins to be dumped onto a belt conveyor which carries them to the location of receptacles that are typically flexible carts commonly referred to as sling carts. From there, the slings must be weighed for proper wash load weight before being hoisted onto an overhead monorail. The articles must then be manually unloaded from the conveyor and placed in the sling carts. As can easily be appreciated, the need for all of these manual operations adds significantly to the overall labor costs. Finally, the vacuum bins and conveyors that transport articles from the bins to the sling carts occupy considerable space. This is particularly unsatisfactory in the case of commercial laundries because they are usually located in high cost urban areas where they are close to their major customers.
The present invention is directed to a method and apparatus for conveying flexible fabric articles in an improved way that avoids the shortcomings of vacuum bin systems. In particular, the present invention provides a venturi system that dramatically reduces the equipment costs, labor costs and space requirements compared to vacuum bin systems, belt conveyors and scales.
In accordance with the invention, a uniquely arranged venturi structure is provided for applying a suction force at a selected location along the conveyor tube system rather than at its discharge end as is necessary with a vacuum bin system. Because the venturi is located along the conveyor tubing, the tubing can discharge the fabric items directly into sling carts or other receptacles while also calculating the combined weight of the sling cart contents, thus eliminating the space occupied by the vacuum bins and the intermediate conveying system as well as the labor that is required to manually unload the articles from the vacuum bins and to later load them into the sling carts. This eliminates the need to manually weigh each sling.
The venturi system of the present invention preferably includes an angled pipe which joins the conveyor tubing at an acute angle and is supplied with air by a blower. An inside pipe is located within the tubing at its juncture with the angled venturi pipe in order to provide a restriction that creates a low pressure area in the conveyor tubing. The resulting suction force draws the fabric articles to the area of the venturi and thereafter transports them a relatively short distance to the discharge end of the conveyor tubing by the positive force supplied by the blower. At the discharge end of the tubing, the fabric articles are discharged directly into receptacles such as sling carts.
An important feature of the invention is the provision of a vent in the conveyor tubing at a location downstream from the venturi. The vent is preferably a screened gap in the tubing which allows a portion of the air to escape. The vent significantly enhances the smoothness and reliability of the conveyor system by partially relieving the air pressure and thereby suppressing pressure fluctuations and other unfavorable pressure conditions that can adversely affect operation of the conveyor system. An adjustable sleeve in the preferred embodiment of the invention allows the width of the gap to be adjusted as necessary.
The invention is further characterized by a closed-loop return system that returns air from the vent to the suction side of the blower. The return system provides numerous advantages, including an increase in the blower suction, a decrease in the pressure on the discharge side of the blower to more effectively convey fabrics through the main conduit, and a reduction in noise.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.